הלכות טומאת אוכלין

All bundles of vegetables in the marketplaces and all the flour and fine flour in the marketplaces can be assumed to have been made susceptible to ritual impurity: the bundles of vegetables, because it is common practice to continually sprinkle water upon them and flour and fine flour, because the kernels of grain are washed and afterwards, they are ground. Similarly, when kernels of wheat are crushed in a mill into two or three pieces in order to be cooked as groats or the like, it can be assumed that they were made susceptible to ritual impurity in all places, whether they are from the marketplaces or from private homes, because they are washed to remove their shells.

All of the above that are assumed to have become susceptible to ritual impurity are also assumed to have contracted impurity, because everyone touches them and they have already become susceptible to impurity. In all such situations, the word of an unlearned person is accepted if he says: "They were not made susceptible to impurity." Needless to say, with regard to other foods about which such assumptions are not made, the word of an unlearned person is accepted if he says: "They were not made susceptible to impurity."

It is assumed that all fish have been made susceptible to ritual impurity. In this instance, if an unlearned person says that they were not made susceptible to impurity, his word is not accepted. For this reason, fish are always assumed to be impure.
Whether fish are caught in a large net, a small net, or a snare, if it was not turned over upon them, they do not become susceptible to impurity. If it is turned over upon them, they do become susceptible to impurity. The word of an unlearned person is not accepted if he says: "I did not turn the snare over upon them." It is assumed that they are impure unless one had the intent to catch them in a state of purity.

It is assumed that all fish brine has been made susceptible to ritual impurity. When even the slightest amount of water falls into pure fish brine, the entire mixture is considered as a liquid. It makes substances susceptible to ritual impurity and it itself can contract the impurity that affects liquids. Therefore it is assumed to be impure.
If wine, honey, or milk fall into fish brine, the ruling is determined by the majority of the mixture. Similarly, if fruit juices become mixed with liquids that are susceptible to impurity aside from water, the ruling is determined by the majority of the mixture. If the fruit juice becomes mixed with even the slightest amount of water, the entire mixture is considered as a liquid that imparts impurity and it is susceptible to contracting impurity as liquids do and it makes other foods susceptible to impurity.
Brine from unkosher locusts does not make foods susceptible to impurity, but it does contract the impurity associated with liquids.

When a person purchases fish brine from an unlearned person, he can make it pure by connecting it to the water of a mikveh. The rationale is as follows: If the majority of the brine is water, the water regains purity because of the mikveh. If the majority is fish brine, it is not susceptible to impurity and the water within the mixture is considered as negligible because of the small amount that is present.
When does the above apply? When one seeks to dip bread in the mixture. If, however, one seeks to cook it in a pot containing water, one type finds its fellow and it becomes significant. Thus the majority of the water is impure, since the minimal amount that was in the brine was not purified in a mikveh.

All that is written in the Torah and the words of Scripture concerning the laws of ritual purity and impurity apply only with regard to the Sanctuary, sacrifices consecrated for it, terumah, and the second tithe. For individuals who are ritually impure were warned against entering the Sanctuary or partaking of sacrificial foods, terumah, or the second tithe while impure. There is no prohibition at all against partaking of ordinary foods while impure. Instead, it is permitted to eat ordinary foods that are impure and partake of ordinary beverages that are impure. Behold, it is written in the Torah Leviticus 7:19: "The meat that will come in contact with any impurity should not be eaten." It can be inferred that that it is permissible to partake of ordinary foods while impure, because the verse is speaking only about sacrificial foods.
If so, what is the intent of the statement: Ordinary food that is a primary derivative of impurity is impure and that which is a secondary derivative is disqualified?. The intent is not that the food itself is forbidden to be eaten, instead, its status is important only when counting levels with regard to terumah and sacrificial foods. For if ordinary food that is a secondary derivative of impurity touches terumah, it disqualifies it and causes it to be considered as a tertiary derivative. Similarly, if it touches sacrificial food, it imparts impurity to it and causes it to be considered as a tertiary derivative, as we explained. Similarly, if a person who ate ordinary food that was a secondary derivative of impurity touches terumah, he disqualifies it.

Just as it is permitted to eat impure ordinary food and drink impure ordinary beverages, so too, it is permitted to impart impurity to ordinary food in Eretz Yisrael. Even as an initial preference, one may impart impurity to food from which terumah and the tithes were separated.
Similarly, it is permissible for a person to touch all sources of impurity and contract impurity from them. This is evident from the fact that the Torah warned a priest and a nazirite from becoming impure through contact with a human corpse. One can infer from this that all other members of the people are permitted. Moreover, even priests and nazirites are permitted to contract impurity from all other sources of impurity with the exception of a human corpse.

All Israelites are warned to be pure on every pilgrimage festival, because at that time, they are ready to enter the Sanctuary and partake of consecrated foods. The Torah's statement Leviticus 11:8: "You shall not touch their carcasses," applies only on the festivals. Moreover, if a person does contract impurity, he is not liable for lashes. During the remainder of the year, one is not prohibited at all.

"The impure and the pure may partake of it" [Deuteronomy 12:22. According to the Oral Tradition, it was taught: an impure person and a pure person may eat from the same plate. Nevertheless, a husband may not eat from the same plate as his wife when she is in the nidah state, nor may he drink with her, nor may he pour her a cup of beverage for her, as we explained. Similarly, a zav should not eat with a zavah because familiarity may lead to sin, for perhaps they will engage in intimate relations.

Even though it is permitted to eat impure foods and drink impure beverages, the pious men of the early generations would partake of their ordinary food in a state of ritual purity and would avoid all of the sources of impurity throughout their lives. They are called perushim.
This is an extra measure of holiness and a path to piety: to be separate from people at large, to hold oneself apart from them, not to touch them, nor eat and drink with them. For setting oneself apart leads to the purification of the body from wicked actions. Purifying one's body leads to sanctifying one's soul from wicked character traits. And the holiness of the soul causes one to resemble the Divine presence, as Leviticus 11:44 states: "And you shall make yourselves holy; and you shall be holy, because I, God, Who makes you holy, am holy."